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About Radiosurgery

To better understand how CyberKnife® works, it is helpful to understand the technology of radiosurgery. Stereotactic radiosurgery (SRS) combines the principles of stereotaxy, or 3-D target localization, with multiple cross-fired beams from a high-energy radiation source to precisely irradiate an abnormal (often-times cancerous) lesion within a patient’s body. The ideal objective is the destruction of the targeted area without damaging any normal tissue outside of the defined target area.

About Radiosurgery
Radiosurgery and conventional radiotherapy are often confused.

  Radiosurgery  Radiotherapy 
Description  Focused radiation delivered precisely to the target sparing surrounding normal tissue Large field radiation delivered to the target and surrounding normal tissue 
Typical Dose Per Treatment  High dose (~ 6 to 25 Gy per treatment)  Low dose (~ 2 Gy per treatment) 
Typical Treatment Duration  1 – 5 treatments  30 – 40 treatments 


Would you rather 4 vs. 40 Treatments?

Stereotactic radiosurgery differs from conventional radiotherapy in several ways. Because radiotherapy does not achieve the same level of accuracy, normal tissues are protected by administering the radiation dose over multiple sessions (fractions) daily for a period of a few to several weeks. In contrast, radiosurgery utilizes highly destructive doses of radiation administered in one to five (1-5) daily fractions. The key to the success of SRS is its ability to precisely target the tumor, firing these high dose beams from multiple angles to avoid sensitive structures (nerves, sensitive areas of the brain, etc.) even as the tumor moves (due to patient movement, breathing, etc.). Prior to CyberKnife, the accuracy of SRS relied on the use of a rigid metal frame fixed to a patient’s skull, immobilizing the head to prohibit movement and minimize damage to the surrounding healthy tissue. This procedure is very effective, but has considerable drawbacks, including the fact that treatment is restricted to only the head.

The CyberKnife radiosurgery system takes this procedure to the next level, eliminating the need for a head frame and allowing CyberKnife to treat tumors anywhere in the body. Perhaps more importantly, CyberKnife is uniquely capable of providing real time monitoring of the target throughout treatment using an advanced image-guidance system, and is able to detect and correct during treatment for some target motion (e.g. due to small patient movements, breathing, coughing).

Stereotactic radiosurgery has been used for more than 30 years to treat benign and malignant tumors, vascular malformations, and other disorders of the brain with minimal invasiveness.

Safe delivery of these radiosurgical high doses require a different treatment delivery technique than the conventional radiotherapy devices. Would you rather treatment with 4 high dose treatments for a chance to cure, control growth, or get pain relief vs. 40 lower dose treatments over several weeks?

CyberKnife provides the means to get the highest dose of radiation to the target with continual detection and correction throughout treatments with no pain, no incision, and little to no recovery time or side effects – allowing you to get back to your life.